Dark Knowledge
by Albertson
Summary: Manipulated by her dark ancestor, Star gains possession of a new spellbook that starts to corrupt her. The race is on to separate her from the cursed tome before she becomes darker than Eclipsa ever was, and to prevent a long forgotten chapter of Mewni history from repeating. This is a sequel story to the Excalibur Saga, so please check that out if you haven't already.
1. Long lost

**Long lost**

After the events of the Cipher War, Queen Moon had the cursed Book of Avalon removed from its island hideaway on Earth and stored securely in a vault in Butterfly Castle, and instructed the guards not to let anyone in to see it, not even her. Star was busy tending to Marco's therapy. Even though the physical scars from being Bill's 'plaything' had mostly faded, the trauma of being tortured day in, day out for a week left a lot of bad memories. Marco would still have nightmares about his ordeal, and it was suggested that Marco spend more time with someone he found soothing, and Star was the best choice for this. Moon was talking to her husband, River, about this very topic over lunch.

"River, dear, do you really think Marco will ever come to terms with his experience?" inquired Moon, concerned.

"I can't even imagine what he must've gone through, but I know he's got a good spirit and a better heart. Dare I say it, but he's quality king material" mused River. Moon chuckled at the last part.

"A human king? That would be something I actually want to see" joked Moon.

"He'd be better than Ludo, that's for sure" replied River. Moon then looked around the dining room, and noted the absence of two important guests.

"Where are Star and Marco, anyway?" quizzed Moon.

"They're in the gardens, having a picnic of their own. Leave them be, dear, please. They remind me of us when we were young" responded River. Moon took comfort in hearing this, pleased that Star found someone that made her happy.

In the castle gardens, Star and Marco were enjoying Star's first picnic. She was curious about this activity, as they never got around to it on Earth, what with school, fights with Ludo and his henchmen and magical adventures. But now that they had an excuse to slow down and smell the flowers, in this case, literally, Star was relishing every moment spent together with Marco.

"If there is one fundamental truth in the multiverse, it's that nachos make everything better" mused Marco, as he was munching down on one.

"These are even better than the ones you make on Earth, what's in these?" agreed Star.

"I experimented with some spices from the royal kitchens. Don't tell your folks" answered Marco.

"My lips are sealed" said Star, flirtatiously, and the two kissed. To Marco, it seemed like forever and a day since he got this type of time to spend with Star, and he found himself wishing it would never end. When they broke apart, Star and Marco lay on the blanket they had laid out on the grass, and fell asleep in each other's embrace.

In the crystal dimension, Rhombulus was patrolling his domain. Since Toffee's defeat, the crystals keeping the evils he had imprisoned were gaining their old strength back. He had feared that, while he was incapacitated during the Toffee incident, and again, on Earth battling Bill and his soldiers, that they had diminished. When he returned from that victory, he found all the crystals as strong as he left them. All, except one. When Rhombulus inspected Eclipsa's prison once he was revitalized , he found it cracking.

"Better check on the crazy lady" Rhombulus muttered to himself. He had missed Lekmet's company in the crystal dimension. He found himself wondering how Moon was able to revive the entire High Commission except for Lekmet. Still, he kept himself busy with his work to take his mind off it. Rhombulus reached Eclipsa's crystal, to find the cracks getting bigger, until the crystal burst open. Eclipsa was free.

"Oh, no you don't!" Rhombulus remarked, and re-crystalized her. What happened next was beyond belief. No sooner had she been re-imprisoned, that the crystal shattered again almost instantaneously. When this happened with Bill, he understood why, Bill's powers were too great to be contained. But Eclipsa was not an all-powerful dream demon, she was just a former queen with dark tendencies.

"I'm afraid that won't work a second time" remarked Eclipsa.

"How did you get out?!" Rhombulus demanded.

"Your queen and I have a contract, once her enemy is dead, I am free to walk Mewni once again" answered Eclipsa, and she showed the ribbon-like markings on her arm to confirm her statement. She made her way out of her former prison, and towards Butterfly Castle. Rhombulus did not fancy his chances against Eclipsa one-on-one.

"Better warn the queen" Rhombulus said, and he cut a scissor portal to the castle in a hurry. When he emerged at the castle throne room, Moon addressed his unexpected approach.

"Please forgive the intrusion, but we have a problem" stated Rhombulus.

"Don't tell me, Eclipsa's free" guessed Moon. Rhombulus nodded to confirm their greatest fears. Moon made off to warn Star, while River doubled the knights inside the castle and Rhombulus proceeded to assemble the rest of the High Commission to form a plan. If Eclipsa could not be re-imprisoned, then the threat she poses would have to be neutralized another way.

Back at the castle gardens, Star and Marco woke up from their impromptu nap, and gathered up their picnic supplies, ready to return to the castle, when suddenly, a figure neither party had seen before approached them.

"To be young and in love, I wish I could re-live those days" the figure mused as she approached. Star and Marco turned to see a gentle-looking woman standing before them. What was unusual is that she had cheek marks similar to Star and Moon, a trait Marco thought was exclusive to the Butterfly family. Star raised her wand at this intruder. Eclipsa took note of the wand.

"So, you're the new wand bearer? Rest assured, I have no interest in that thing. I only want to talk" assured Eclipsa. Star recognised her from the tapestries.

"You're Eclipsa, the queen of darkness who fled Mewni" stated Star.

"Queen of darkness, is that what my tapestry says now?" asked Eclipsa.

"Yeah, I may not love monsters as you do, but I know that not all of them are bad. One of my best friends is a monster. In fact, I'm the god-mother to his tadpoles" answered Star.

"Really? It's nice to know Mewni's got more progressive since I was last here. Tell me, what has your mother told you about me?" inquired Eclipsa.

"That you created a whole chapter of dark spells. I found the All-Seeing Eye spell really useful at times" replied Star. Marco was disturbed by this.

"Did you, by any chance, use that spell to spy on me?" quizzed Marco. Star saw no point in lying.

"I wanted to see how you were after I left to fight Toffee, you were so sad, and I missed you" confessed Star. Marco appreciated her honesty.

"Just promise me you won't spy on me again" Marco said, forgivingly. Star promised that she wouldn't.

"I even found a way to reach through the looking glass one time, to try and rescue Glossaryck" added Star.

"Speaking of Glossaryck, where is he, and the spell-book?" asked Eclipsa.

"The book is gone, along with your chapter. We got Glossaryck back, but he's not himself" answered Star.

"That's not surprising. He and the book are bound together. When one goes, it affects the other. He can be bound to another spell-book. I can do this, but we'll need a book to bind him to" explained Eclipsa. Just then, Moon came bursting into the gardens, backed up by some knights.

"Seize her!" Moon ordered, and the knights grabbed Eclipsa. Star was bemused by this.

"Moon, dear, it's good to see you again. How did that spell work out for you?" inquired Eclipsa.

"You stay away from my daughter!" Moon seethed. Marco could sense tensions were running high.

"The last thing I want is to be involved in family drama. Can I meet Star at the castle, please?" Marco added. Moon gestured that he could leave, and the knights let him pass.

"Mum, is this really necessary? We were just talking and catching up" Star asked in total shock.

"Star, this is the woman who abandoned her people so she could run off with a monster! You've seen her spells, and what they can do. She's evil!" Moon insisted.

"She's also the woman who can put Glossaryck back to normal. All she needs is a new spell-book" Star replied. Moon was horrified. She didn't tell Star about the Book of Avalon, for her own safety. But if Eclipsa knew it was being stored here, or worse, if she ever got a hold of it, Moon did not want to think about it.

"Throw her in the dungeon!" Moon ordered, and the knights took her away. Moon went with them, and Star followed. No-one spoke, and Moon told Star to wait in the dining room for her, and that they will discuss the matter when she arrived from the dungeons. Once Eclipsa was secure in her cell, Moon made to meet Star in the dining room.

"Are you alright, Star?" Moon asked, concerned.

"I'm fine, she approached us, not the other way around, before you ask that question" Star answered. Moon was slightly relieved to hear this, as she didn't want Star seeking out her dark ancestor.

"What, exactly, did you two talk about?" quizzed Moon.

"Just some stuff about my friendship with Buff Frog, her spells, and putting Glossaryck back to normal" Star recounted.

"Glossaryck can't be put back to normal without a new spell-book, and your notebook of spells is not compatible, it needs to be Mewni-made, and making a new one takes time" explained Moon.

"Even so, she is family. Whatever she did in the past, does it really warrant imprisonment and being shunned by the rest of us? I, personally, am curious about her" reasoned Star.

"That's only natural, but she is dangerous. She can make you do things you don't want to do. Please, stay away from her. For your own good" Moon pleaded.

"She didn't seem evil to me" Star countered.

"I thought the same thing when I first met her. That's how she gets into your head. I should never have made that deal with her, even if it did end the war" Moon reflected.

"You said yourself you didn't know what else to do. I probably would've done the same thing in your position" Star consoled.

"Let us hope you never end up in that position" Moon concluded, and they hugged it out.

Later that evening, Star and Marco were getting ready for bed, when Marco approached Star, eager to see if everything was OK.

"Star, I'm sorry I bailed. It's just I always consider family issues things that should be left in the family" Marco said, apologetically.

"It's fine, nothing I couldn't handle on my own. But I can't help but have questions about her" Star replied.

"What did your mum say about her?" Marco asked.

"Not much, only that she ran off with a monster, leaving Mewni without a queen for a time, and invented a lot of dark spells" answered Star.

"That would make her a bad ruler, but not necessarily a bad person. She seemed sweet enough to me" Marco responded.

"Do you have any black sheep in your family?" Star inquired, hoping to find some common ground.

"We don't talk about him, but my uncle had issues. Fell in with a bad crowd, lost his job and had more than a few run-ins with the law. Eventually, things got so bad the family had to disown him. This was all before I was born, but I still wonder about him, sometimes" Marco explained.

"You never thought to seek him out on your own?" Star pressed further.

"Once or twice, then I found out why he's in jail now. I won't say what he did, but it's pretty sick, and after that, I was content with pretending he didn't exist" Marco recalled. With this story, Star almost understood why Moon had such misgivings about Eclipsa, but it didn't help that Moon would not tell her what exactly Eclipsa did that earned her an eternity in a crystal prison.

The time came for Star and Marco to climb into their bed and let sleep take them. Star and Marco had been experimenting with sleeping in the same bed together since the Cipher Liberation Day party. Both found it more comforting than usual. So much so, in fact, that when Pony Head came to visit, she had been teasing them about when they were expecting Mewni's next princess. This, understandably, had Moon and River very concerned, but they allowed it to continue, for therapeutic reasons, to speed up Marco's recovery.

While Marco slept easily, Star lay awake. The questions she had about Eclipsa still rattled in her head. She decided that the best source of answers was Eclipsa herself. She climbed out of bed, and snuck into the castle dungeons. This was easy for Star, because in all the time she lived here, she could memorise the knights' patrols and avoid them blindfolded. Once she made it into the dungeon, she found Eclipsa's cell, and quietly got her attention.

"Star, what are you doing here?" quizzed Eclipsa, in a hushed tone.

"Sorry, but I still have so many questions about you and what exactly happened between you and the High Commission" Star explained, also hushed. Eclipsa saw this as a chance to capitalise on Star's curiosity.

"Let me out, and I'll tell you everything you want to know" Eclipsa bargained. Star then pickpocketed the keys from a nearby guard, sleeping at his post, and opened Eclipsa's cell, then undid her irons.

"Now that's done, I'd like to pick something up" Eclipsa added. Star was confused. She looked around, but found no evidence that anything was seized from Eclipsa when she was incarcerated. "I overheard some guards gossiping about a book that Moon has locked away in the vault. If I'm right, we can restore Glossaryck with it" she clarified. Star was shocked. All she wanted was answers about Eclipsa's past, and yet here she is, contemplating theft from her own house.

"I am not stealing anything for you!" Star retorted, and now she wished she brought her wand with her.

"It's just a book, what harm could it possibly do? Besides, you need to complete your magical training, and without Glossaryck, your chances are not good" assured Eclipsa, frankly.

"We're making another one" Star argued.

"That'll take too long, Star. Do you want Glossaryck back or not?" replied Eclipsa. Star thought about this. She did still hold some resentment over Glossaryck ditching her for Ludo, then Toffee. On the other hand, she did need training. Eventually, Star came to a decision.

"For Glossaryck, not for you" Star decided.

"Fair enough" Eclipsa said, and the two made their way to the vault. Eclipsa was able to distract the night watch away from the doors, and magically pick the lock. When Star and Eclipsa went inside the vault, all they found was the dusty, old tome Eclipsa had mentioned.

"My mum had this locked away? Thing looks like it could fall apart at any moment. You want to bind Glossaryck to this?" asked Star, bemused.

"The older the book, the faster he will recover. Now, let's get it out of here" Eclipsa instructed, and the two made off with the book. Star hid the book in hers and Marco's room amongst the others, and she climbed back into bed, thankful Marco did not notice her absence.

Author's note: It has been a while since my last story, I hope I didn't keep anyone waiting too long. For those of you who will say to me that Star would never steal from her family, I wanted to capitalise on a line from the promo, that Eclipsa can make people do things they don't want to do. Keep in mind this was written before Season 3 started in earnest, so please forgive me if I get anything about Eclipsa wrong, I just find her an intriguing character I really wanted to write for. This is a sequel story to the Excalibur Saga, so for those of you reading this before that story, check that one out first, so you understand some of what is written here. The usual disclaimers, I own nothing, Daron Nefcy owns SVTFOE, Alex Hirsch owns Gravity Falls, and Disney owns them all. Enjoy.


	2. Gift bearer

**Gift bearer**

After breakfast the next morning, Star thought it would be a good idea to read the book taken from the castle vault before binding Glossaryck to it. To that end, she took it to the castle gardens and began sifting through its pages. Eclipsa, who made the rose tower in the gardens her home, had sat down with her. After all, if she was to be the one to actually bind book and Glossaryck together, she should also read the book.

"Why did Mum hide this away? These spells could do a lot of good. Take this one: revitalise dead soil in war-ravaged lands. I know a few places that could use that" mused Star.

"What about this; bring fresh water to the driest deserts. I'm a big fan of the spell that promotes flower growth" added Eclipsa.

"I know what we should do today. Why don't we bring the power of these spells to those most in need. It wouldn't be very princess-like to leave my people lacking their basic needs" suggested Star.

"That sounds delightful, plus I need the 'good behaviour' points from your family" agreed Eclipsa. Ever since getting out of her crystal prison, Eclipsa had yearned for the chance to prove to her family that she wasn't as dark as everyone made her out to be. Bringing the people of Mewni whatever they needed, in her opinion, would certainly help.

"I'll just go get Marco" piped Star.

"The boy you're with? This little venture of ours is the perfect opportunity for me to get to know him better. I feel like I should know the people who will eventually become my in-laws" teased Eclipsa.

"Have you been talking to Pony Head?" asked Star.

"No, but from what I observed the other day, it's only a matter of time" answered Eclipsa. Star fetched Marco after telling him what they had planned, and told her mother and father they were going to do some charity work around the kingdom. Moon and River wished her well, and Star, Marco and Eclipsa were off to various parts of the kingdom to perform their miracles.

Their first stop was the corn fields, or rather, what was left of them. It had been some time since the rats took over the kingdom, but the damage was still there.

"So, this is what this Toffee character had wrought upon the kingdom. No wonder Moon wanted him gone so badly" mused Eclipsa.

"Yeah, we're still rebuilding after his take-over. Let's get to work" Star pressed, and she pulled out the book, and opened it to the spell on re-growing damaged crops.

"Star, I've never seen that book before. Where did you find it?" inquired Marco.

"Mum had it locked away in the vault. Don't know why, though. Thing looks like it hasn't been read in centuries" answered Star. Marco was scared at this answer.

"If Moon locked that away, it must be for a reason. Never judge a book by its cover" cautioned Marco.

"Just wait until you see one of its spells in action. You'll change your tune. Now, let me focus" rebutted Star. She read the passage, and recited the spell she needed:

 _I beseech you now, on this land_

 _Bring the power to my command_

 _Here in this place, scarred by war_

 _Make these fields fertile once more_

When Star was finished reciting the spell, the corn fields were revitalised, and ears upon ears of corn literally shot up into the air. In seconds, the fields were flourishing, and the entire farmland looked like no-one had even been here. The farmers could not believe their eyes. They turned to Star, and their gratitude was immediately obvious.

"Bless you, girl. You're a true princess" thanked one farmer.

"You're a credit to your family" complimented the other. Star was shaking hands and helping the workers gather up harvests to either eat themselves, or sell at the markets. There was enough corn to feed the whole of Mewni and more. Star advised them to share this exceptional bounty with any willing monsters, eager for equality. The farmers agreed to this, and the trio left for their next stop.

"Star, I'm impressed. What else can that book show us?" quizzed Marco, his scepticism long gone.

"The best is yet to come" answered Star, and they set out to ease Mewni's pains. At their next stop, Star performed a spell no-one had ever seen before or since. In one desert area, Star conjured up a mighty river, which spawned greenery and brought sea trade to local villages. Star followed up this act of almost god-like kindness with a few words on proper resource management, as Marco said to her, if you gave a man a fish, he would eat for a day, but if you taught him to fish, he would eat for a lifetime.

Other stops included a land in the midst of a plague. Star had used a mass healing spell to cure these people's ails, as medicine was running low and the people did not have enough for everyone. A storm, threatening to destroy homes and ruin fields was blasted away and replaced with the usual seasonal rainfall, and in another village, Star calmed a rampaging beast, pulling out the thorn in its foot. It had scampered away without hurting a soul. The end of the day soon came, and the trio was exhausted.

"I think we've done enough charity work for one day. Let's go home" Star suggested. Marco and Eclipsa agreed, and they scissor-portaled home.

"I'll begin preparations to bind Glossaryck to that book tomorrow morning. There is no doubt its pages have a lot more to offer" stated Eclipsa.

"See you then" replied Star, and she and Marco made for their room.

In the throne room, Moon and River were discussing Star's decision to do her charity work.

"I think it's wonderful Star is giving back to her kingdom, like a princess should" said River.

"Yes, she has improved. I do hope she's not over-doing it. People need to solve their own problems some of the time. There is such a thing as being too generous" responded Moon.

"It's just charity work. What harm could it possibly do?" asked River, rhetorically. Just then, a knight came into the throne room.

"Forgive me, Your Majesty, but this is important. It's Eclipsa, she's escaped her cell" reported the knight. Moon and River jumped off their seats and rushed to the dungeons. Indeed, Eclipsa had escaped.

"Who was keeping watch here last night?" inquired Moon, and the night watchman was brought before her.

"Your Highness, how wonderful to see you" greeted the night watchman, scared witless.

"What. Happened. Here?" seethed Moon.

"I, uh, I don't know. It was dark, I couldn't see" the watchman lied. Moon was not convinced.

"I'm sure it was very dark, with your eyes closed from falling asleep, AGAIN!" Moon retorted, and she had the watchman thrown out of the castle. Moon was pacing, the High Commission having been alerted to Eclipsa's escape.

"Please tell me this can't get any worse" Moon said, and then the guards assigned to guard the vault had arrived.

"Your Majesty, we regret to report that the book you had us guard is missing" stated the guard.

"WHAT?!" yelled Moon, so loud, practically the entire castle and half of Mewni could hear.

"Hold on, what book?" inquired Omnitraxus.

"After the Cipher War, I had the Book of Avalon hidden here and its existence kept a secret. Now I see I should've destroyed it" confessed Moon.

"With respect, what were you thinking? Keeping Mewni's darkest queen and its darkest artefact in the same building is just asking for trouble" rebuffed Hekapoo.

"I thought I could dispel the curse and put it in a display. It is, after all, a part of Mewni's history" answered Moon.

"So is Eclipsa, yet we had her crystallised and hidden away" countered Rhombulus.

"I know, I know. If Eclipsa has the Book of Avalon, it'll mean nothing but catastrophe. The sooner we find her and the book, the better" concluded Moon, and she and the High Commission left to find their targets.

Back at Star and Marco's room, Star put the book back on the shelf, and settled down to sleep.

"You know, I've never seen spells like those you performed today, even that time we were fighting Toffee. I just hope the people don't start seeing you as some sort of god" mused Marco. Star laughed at this.

"What would I be the god of? Nature, the arts, tough choice" listed Star.

"Then don't choose. Just be Star Butterfly, that's good enough for me" inspired Marco.

"Yeah, being a god would get boring after a while. All those people bowing to you, offering gifts. I get enough of that right here. But do all those gods have you? I think not" said Star, and she and Marco kissed goodnight.

Star was having the most peculiar dream. She was in the library at Echo Creek Academy, an area of the school she rarely visited while she was there. She knew right away that this was a dream, because she saw Eclipsa at the reception desk.

"Eclipsa, how did you enter my dreams?" asked Star.

"I didn't. I'm not Eclipsa. I'm just using her form to talk to you, as she is a figure you are comfortable with. If you wish, I can take the form of another, like Marco for instance" answered the figure using the form of Eclipsa, or at least it was, until it took the form of Marco.

"Stop doing that, you're freaking me out" scolded Star, and the figure stuck with its Marco form. Star then asked what it wanted.

"Oh, nothing. You've been using my spells to aid your kingdom. I came here to express my admiration" explained the figure. Star put two and two together.

"Did you write the book?" inquired Star.

"Oh, yes, and there's more I can show you, like bringing dear Lekmet back into this world" answered the Marco lookalike. Star did not know what to think of this development. While she and Lekmet never really spoke, he was, while he was alive, a valued member of the Commission, and maybe he could shed some light on Eclipsa.

"What else can you show me?" asked Star.

"I can help keep your kingdom safe against all who would threaten it, to prevent another Toffee, and give you answers about Eclipsa" offered the figure. Star thought about this, and came to a decision.

"Show me, please" instructed Star.

"With pleasure" responded dream Marco, with a menacing smile.

Author's note: Apologies if the wait between chapters seemed long, I am experimenting with writing chapters only once a week to help properly flesh them out. This chapter also highlights my complete inability to write spells. I am many things, but a poet, I am not. I am also not the owner of anything depicted here. Daron Nefcy and Disney own SVTFOE. Enjoy.


	3. Lost in the pages

**Lost in the pages**

The next day, Star was in the rose garden, reading as usual. Marco had noticed that Star spent an abnormal amount of time just sitting on a garden bench, her face buried in the book's pages. This seemed unusual to him. Marco had always figured Star to be the adventurous type, not content with sitting in one place for more than five minutes. When Marco had suggested they get out of the castle and get some goblin dogs one time, Star brushed him off without even looking up from the book.

"I'm telling you, this is not normal. Something is wrong with my girl!" remarked Pony Head. She, too, had suggested that they get up to their usual hijinks, only to be brushed off in a similar manner.

"You're telling me. She hasn't moved from that bench since this morning" observed Marco. He had considered telling Moon and River, but that would mean telling them that Star stole from their vault, and he did not wish to see Star in trouble if he could help it. Besides, Moon was not around most of the time. River had told Marco she was on important business with the High Commission.

Eclipsa had emerged from her tower with everything she needed for the binding of Glossaryck to the book, and Star finally moved from her perch.

"Everything's ready, dear. We can start whenever you want" said Eclipsa.

"Thanks, Eclipsa. I'd like to start as soon as possible. The sooner Glossaryck is bound to the book, the sooner he can show me more of its secrets" Star replied.

"You've been reading that book for hours. Surely you know everything about it by now" countered Marco.

"You've got to let the knowledge sink in, Marco. There's still so much to uncover" mused Star.

"If only you were this studious on Earth, you would've gotten better grades" retorted Marco. The preparations for the binding ritual were complete, and Eclipsa began incantations.

"So, when this weird, spooky ritual thingie's done, we get our old Star back?" asked Pony Head.

"I hope so" answered Marco, unsure if this was true. Then, suddenly, the door to the rose garden burst open, and Moon and the High Commission started bursting in. But before they could interrupt the proceedings, Star got in between them and the ritual site.

"Step away, princess. This is very dangerous" cautioned Rhombulus, but Star was not budging.

"This ritual must not be interrupted" stated Star, and she drew her wand at the High Commission. "Any attempt to stop this will be met with force" she added. Pony Head was immediately surprised at her best friend's behaviour, and stepped in to try and talk some sense into Star.

"Are you serious girl? This is the High Commission you're talking to. You're no match for them" reasoned Pony Head.

"Don't worry, I've upgraded my arsenal with spells from the book. I'll be fine" assured Star. Moon was horrified.

"Star, have you been reading that book?!" Moon demanded.

"She hasn't stopped reading it. I'm sorry, Star, but this isn't you. I don't know what that book is or where it came from, but it's changing you" pleaded Marco.

"It's just a book, don't be so dramatic!" snapped Star.

"Just a book? Star, that's the Book of Avalon! It corrupts any who dare to read its pages, twisting and turning them into a mockery of everything they once stood for. It's evil!" explained Moon, urgently. But again, Star was having none of it.

"You see evil everywhere, dear mother. Eclipsa, Buff Frog, the book. Next, you're probably going to tell me Marco's evil" retorted Star. Moon continued to plead with Star to see reason, but she would not budge. Then, out of the corner of Star's eye, she could see Omnitraxus sneaking around her to grab the book.

"Not so fast" warned Star, and she fired a spell at Omnitraxus. What happened next scared everyone, even Eclipsa. The spell Star fired trapped Omnitraxus in an electrical bubble, shocking him continuously, leaving him in immense pain. Star threw the caged Omnitraxus against a wall, and the bubble dissipated. Moon and the rest of the High Commission went to check on Omnitraxus. He was still in severe pain, but otherwise OK.

"Star, enough! Stop this now!" ordered Moon, but the High Commission, angered at their fallen comrade, were out for blood.

"That does it! It's the crystal for you, princess!" spat Rhombulus, and he prepared to encase Star in one of his crystal prisons, only for Star to shoot another spell at him. This one surrounded Rhombulus in conjured water and froze into ice, ironically encasing him in an ice prison.

"It is on, now, blondie!" seethed Hekapoo, and she lunged at Star with her scissors, only for Star to conjure a gust of wind so strong, it sent Hekapoo flying out of the garden. When she was in mid-air, Star caught Hekapoo with an electric rope, essentially shocking Hekapoo while Star threw her to the ground. When she turned around, she found Marco approaching the ritual site.

"What do you think you're doing?!" inquired Star.

"I'm ending this now! This book needs to be destroyed!" yelled Marco, and he made for the book. But before he could reach the cursed tome, Star put him in a similar shock bubble as she did Omnitraxus. Marco felt the all too familiar pain, the kind he wanted to forget. It was brief, as Star released him after moving him to the garden entrance.

"That power. I've felt that only once before. In his castle" recounted Marco.

"What do you mean, his castle?" quizzed Star.

"What Marco is trying to say is that the Book of Avalon was created by Bill Cipher. The story of the fallen prince is actually Mewman history disguised as a fairy tale" explained Moon. When Star heard this, she started thinking. The weird dream she had last night did sound like something Bill would conjure up. But Bill was defeated, there was no way he could hurt anyone ever again, let alone be influencing her.

"Bill's gone, you saw that yourself" rebutted Star.

"I know he is, but his creation still exists. The sooner we destroy it, the better" countered Moon. Just then, Star started grabbing her head, like she was having a really bad migraine. When Star rose her head up again, Moon and Marco saw, to their horror, that Star's pupils were vertical slits.

"Star is not available at this time. Leave a message and she'll get back to you" taunted Bill-Star.

"No! You're dead!" remarked Marco.

"That part of me that resided in my body is, yes. But the part of me that resided in the book is alive, well, and eager to bring my original self back" responded Bill-Star.

"Not a chance! Now give me back my daughter!" Moon demanded.

"Wait, Bill Cipher's real? Wasn't he just a fairy tale?" wondered Eclipsa.

"Nope, I'm the real deal, Eclipsa, and I gotta say I'm a huge fan of yours. Your magic is the stuff of infamy. You deserve a little something for making all this possible. How about I return your monster lover to your side and we'll call it even" offered Bill-Star.

"You can do that?" inquired Eclipsa.

"With the book, I can do anything. Resurrect your monster squeeze, give you your throne back, you name it, and it's yours as a thank you gift" clarified Bill-Star. Eclipsa thought about this, and came to the decision she thought was right.

"Under normal circumstances, I'd leap at that offer. But you manipulated my grand-daughter and took her body against her will. I can't forgive that" decided Eclipsa.

"Don't play the sappy grand-mother card on me, lady. Need I remind you that you were the one who convinced Star to steal the book. You were the one who promised Star her magic teacher back, and you were the one who suggested she keep it close to her at all times" reminded Bill-Star.

"You know, I used to say, all knowledge is good knowledge. But now, I'm starting to realise, maybe some things are best left unknown. Star, if you can hear me, I'm so sorry I got you into this mess" said Eclipsa, apologetically, and she made to destroy the book, only for Bill-Star to conjure vines to restrain her.

"What a pity. We could've gotten along famously. Instead, you had to join the losing side" retorted Bill-Star. Moon decided enough was enough, and also lunged for the book.

"I wouldn't do that if I were you. Right now, Star is lost in the book's pages. Destroy the book, and you destroy her" warned Bill-Star. Moon stopped her attack.

"That's better. Now, if you don't mind. I'll be taking this somewhere we won't be rudely interrupted" concluded Bill-Star, and she grabbed the book, conjured a portal and disappeared through it. Moon then saw to freeing Rhombulus from his ice prison, and even Eclipsa from her rose restraints. She ordered healers for Omnitraus, Hekapoo and Marco, who was shaking uncontrollably.

"No, not again" whimpered Marco, over and over again. It was obvious to Moon, that he was having flashbacks to the time where he was Bill's prisoner. After everyone was bandaged up, Marco having to be sedated to calm him down, Moon and the others began planning their next move.

"Before we do anything, we need to know what spells are at Bill's disposal. What can he make Star do?" asked Hekapoo.

"I think I may know someone who might answer that question" suggested Moon, and she activated her mirror.

At the Excalibur Institute, Albert was busy briefing the new president on the organisation, its goals and activities. The Cipher War left a lot of bad press. The few remaining world leaders who knew of Excalibur's existence had lost faith in the institute's ability to handle outside threats, and rumours were still circulating about Excalibur, leading some radical groups to demand answers from their state representatives.

"We can't play off Excalibur as a mere rumour forever, Albert. Sooner or later, the public will find out, and when they do, I'll be faced with a flurry of questions I don't know how to answer" pressed the president.

"I know the situation is bad, Madam President, but we are doing our best to ensure that doesn't happen. Right now, cyber division is sowing the seeds of doubt in these conspiracy theories, introducing false evidence and misdirecting those with even the slightest suspicion. With any luck, this whole thing will blow over" explained Albert.

"I don't rely on luck, and neither should you. I'll keep your institute secret as long as I can, but when the heat comes down, you're on your own" concluded the president, and she terminated the call. Kilstone, Albert's XO, then entered the room.

"Sir, IDC division just got a message from Mewni. Queen Moon is requesting to speak with you" Kilstone briefed. The IDC stood for Inter-Dimensional Communication. Using technology salvaged from Bill's fearamids, Excalibur was able to recreate the method with which Bill used to send messages to and from the Nightmare Realm.

"This sounds important. I'm on my way" Albert said, and he went to his office. He went to a mirror and pushed the button on its side. A call from the Queen was received.

"Is there something I can help you with, Your Majesty?" inquired Albert.

"I'm afraid I have bad news. The Book of Avalon has been stolen" informed Moon. Albert rarely ever showed fear, but in this case, he could not imagine what could happen next.

"By whom?" Albert quizzed.

"My daughter. Believe me, she had no idea of the book's nature, and now Bill has her. We need to know what spells are in the book if we hope to free her" Moon answered.

"If she's lost in the book's pages, then she's on her own, unless you have a way of entering the book and retrieving her. There is always the chance Star could fight her own way out. Knowing her, she's preparing to do exactly that as we speak. As for spells, there were certain spells near the end of the book I never got the chance to use, thankfully, but I know what they can do" explained Albert.

"What can these spells do?" quizzed Moon.

"You got your basic attack spells. If Star has already been corrupted, you've probably seen those first hand. Deeper in the book, you have curses with no end in sight or any hope of release except death, and at the very end, is the Demonic Bargain" outlined Albert.

"This 'Demonic Bargain' wouldn't have anything to do with restoring Bill, I hope?" asked Moon.

"Well, to summon a demon from the Land of the Vanquished, you have to offer the land a demon in exchange. Do you know any demons Star's familiar with?" inquired Albert.

"Tom!" Moon and Marco said together, and they made for the underworld to warn him.

Author's note: There are three reasons why this took so long. 1: I wanted to keep away from potential Pokemon Ultra Sun and Moon spoilers, as dataminers hacked early copies of the game, so I kept away from that side of the Internet, and felt that browsing DeviantArt and would prove risky to that effort. 2: I wanted to wait until the SVTFOE two week episode binge was over to get a better idea of Eclipsa's character before I took any stories with her any further. 3: When I was writing the Excalibur Saga, I was making it up as I went along half the time, and I swore to myself I would never do that again. I apologise if the wait seemed like an eternity. The usual disclaimers, I own nothing, Daron Nefcy owns SVTFOE, Alex Hirsch owns Gravity Falls, and Disney owns them both. Enjoy.


	4. Deal with the devil

**Deal with the devil**

Star found herself in a strange place, full of what looked like book pages, but all of them had eyes in them, and they were all staring at her. She felt uncomfortable, and wanted to leave as soon as possible.

"In a hurry, princess?" taunted a familiar voice.

"Bill, is that you?! What have you done?!" Star demanded.

"Oh, not much, other than take your body and mind, and got you a new title as Mewni's Most Wanted" answered Bill. Star remembered what happened at the rose garden, how she brutally attacked the High Commission, and worst of all, Marco, and felt nothing but shame.

"What have I done?" Star half-cried to herself, while Bill was laughing at her pain and anguish.

"Don't get so down on yourself, princess. Your corruption and my restoration will be forever remembered as the starting points of Mewni's new age of nightmares. You can't stop what's coming, but feel free to try. I could use the entertainment" Bill goaded. Star chased after him, but Bill was long gone, leaving Star to ponder her fate, thinking of ways to get out of this situation.

In the land of the living, Bill-Star was examining what looked like gooey remains. Bill-Star gathered as much of this as she could, not easy because most of it was crushed under a pillar.

"Not much here, but I can work with this" Bill-Star mused to himself, and he started casting a resurrection spell. After a while, the gooey remains took form, and not before long, a lizard wearing a suit now stood where the remains once were. The lizard lay eyes on the princess.

"Now this is interesting. Murderers do not usually bring back their victims" Toffee observed.

"No, they don't. But then again, I didn't murder you" Bill-Star explained. Toffee started examining Bill-Star more closely, and noted that her pupils looked like someone else was in control.

"You didn't, did you? Then, please tell me, what is it you want?" Toffee inquired.

"The name's Bill, and I'm here to make a deal with you. There's someone I need you to collect for me. I'm holding a little shindig and he's the guest of honour. Do this, and we're even. Your newly restored life will be yours to do whatever you see fit, my friend" Bill-Star outlined. Toffee thought about this. While he didn't like the idea of being indebted to someone else, this Bill did bring him back from the dead.

"Alright, who is it you want collected?" Toffee asked.

"The prince of the underworld, Tom Lucitor" Bill-Star answered.

"Forgive me, but if I'm going to go after royalty, I'll need a little more incentive. If past experience is anything to go by, princes and princesses can prove painfully stubborn" Toffee pressed.

"How about I throw in the chance for you to get revenge on the one who taught Moon to sever your finger, not to mention Moon herself?" Bill-Star offered. Toffee laughed at this.

"Now you have my attention" Toffee concluded.

At Butterfly Castle, Moon, Eclipsa and Marco were scissor-portaling to the underworld to warn Tom. Moon was grateful to Eclipsa for trying to save Star, and permitted her to come along, but that did not mean she trusted her. Tom noted their arrival.

"Marco, what's up, buddy? Why is Queen Moon with you? And who's this?" Tom quizzed, gesturing at Eclipsa.

"To answer all your questions; this is Eclipsa, Star's nine-times great-grandmother, and two, Moon and I are here to warn you, Star's coming for you" Marco explained.

"Star's coming? No offence, but I don't think I'm ready to see you two go all googly eyed over each other yet" Tom remarked.

"Trust me, if Star comes, it won't be pretty. She hasn't been herself lately" Marco clarified.

"Her body and mind have been taken over by a demon called Bill C-" started Moon, but mid-sentence, Tom put his hand over her mouth.

"Sorry, but that name's forbidden down here. We should go to my room, talk more there, away from prying eyes" Tom insisted, and they went to his chambers.

"Why is 'his' name forbidden in the underworld?" Marco asked.

"We don't talk about it. His powers rivalled the most powerful of the underworld's rulers, but where we learned to contain our abilities to this realm, the one whose name must never be mentioned had no qualms about starting wars, inciting riots and generally causing chaos. Eventually, the underworld leadership banished him to the Nightmare Realm, and passed an ancient edict stating that no soul ever speak his name in the underworld's depths, an edict still enforced today" Tom explained.

"I see, well, Star started reading one of his books, and now she's lost in its pages. He means to use her to enact something called the 'Demonic Bargain', and he needs you to do it" Moon said, warning Tom of the current threat.

"The Demonic Bargain's impossible. You'd need another demon in the Land of the Vanquished to pull it off" Tom shrugged off.

"That won't be an issue" said a voice that sent shivers down Moon and Marco's spine. They turned around to see Toffee standing before them, flanked by nightmare soldiers.

"Didn't you say he was dead?" Tom asked.

"Oh, not anymore, my dear demonic friend. I have my generous benefactor to thank for that, and all he wants in exchange is you. I really don't like excessive violence, so if you'll please come with me?" Toffee ordered.

"Not a chance!" Tom responded.

"The hard way it is, then" Toffee sighed. The nightmare soldiers advanced on Moon, Marco and Eclipsa, while Toffee made to grab Tom. Moon and Eclipsa blasted the soldiers away with their magic, while Marco unleashed a flurry of punches and kicks, regretting that he didn't fetch his sword from Hekapoo's realm before coming here. Tom encased Toffee in a tornado of fire he conjured, and he thought the battle done.

"That was easy" Tom mused, but skeletal hands burst from the vortex, gripping Tom's shoulders tightly, and the rest of the form emerged, and began to regenerate back into Toffee.

"That's cheating!" Tom pouted, before being dragged via portal to Bill-Star's current location. Marco, Moon and Eclipsa were barely able to force the soldiers off them and jump through the portal before it collapsed.

"Well, well, well. Nice of you to join us, Your Highnesses, and my old plaything. How have you been?" Bill-Star taunted.

"Give us back Star!" Marco demanded.

"No need to get hostile, once I'm done, you can have your little girlfriend back, along with that old man Glossaryck, not that he's much use anyway" Bill-Star rebuffed.

Inside the book, Star was wandering through the pages, when she ran into Glossaryck sifting through the texts without a care in the world.

"I wouldn't do that, if I were you. This book changes people" Star warned.

"Really, Star. How can a book change people? Did it force you to continue reading?" Glossaryck interrogated. Star was both amazed that Glossaryck can form a complete sentence, and a little put off that Glossaryck was talking back to her.

"No, but the book's author was very persuasive" Star countered.

"Need I remind you that you were the one who stole the book, used its spells and attacked the High Commission when they tried to stop me being bound to it? Now, if you'll excuse me, I need to get myself unbound" Glossaryck dismissed. Star was having none of this.

"Wait, you can bind and unbind to spellbooks at will?" Star inquired.

"Star, I'm bound to the role of family teacher, and this book does not contain anything written by a Butterfly, so yes, I can unbind at will" Glossaryck answered.

"Take me with you" Star asked.

"What would that accomplish? What would you have learned? Besides, there's only room for one. Don't worry, I know you can do it" Glossaryck encouraged, before disappearing. Star was angry at being left behind, but pondered Glossaryck's words. Star thought about her predicament, and the events leading up to it. All the time she had been here, she thought that Bill tricked her into reading further, attacking the High Commission and letting Eclipsa bind Glossaryck to the book. But he had been right. Bill did not trick her into any of those actions. Star chose to do those things, out of a misguided lust for knowledge.

Then, it came to her. Star had to accept what happened, and the consequences of those actions. But there was also a revelation. Why would Bill hammer it into Star's mind that she was trapped? The answer, Star thought, was that the only reason she was trapped in the book was because Bill made her think she was. She tried imagining a way out, and to her surprise, flashing arrows pointed in a direction. Star followed, and she came to an Earth style emergency exit.

"Where do you think you're going?!" Bill demanded.

"I'm leaving, now!" Star yelled, and she kicked down the door and ran through before Bill could catch her. She was out of the book, but not back into her own body. Instead, she found herself floating above a ritual site. She saw Tom strapped to a table, obviously meant to be some sick sacrifice, and Toffee, standing alongside her, or to be more precise, Bill in her body, and finally, Moon, Eclipsa and Marco tied up together, nightmare soldiers watching them. Star had seen enough, and lunged towards her own body. Bill-Star started clutching his head again.

"No, not now! You think you can win?" Bill-Star struggled, until Star was able to take over, for a brief instant.

"Destroy the book, quickly!" Star urged, and then the High Commission came bursting in, freeing Tom and the others, then dispatching the nightmare soldiers. Toffee grabbed the book before anyone could damage it, and he and Bill-Star vanished in the confusion.

"Is everyone alright?" Omnitraxus asked, concerned.

"We're fine, but Star's still under Bill's control. She was able to talk to us for a fraction of a second at most" Moon answered.

"I think I can explain this" Glossaryck chimed in, and he told them of what happened inside the book, and his speculation that Star broke free. "It is my understanding that the reason Star was not able to take full control was because Bill still has control over her conscious mind. If we render the body unconscious, Star can climb in and regain total control" Glossaryck further postulated.

"Easier said than done" Marco added.

"We have to try. In the meantime, we need to get Tom to Butterfly Castle, he'll be safe there" Moon suggested, and they made their way to the castle. A room had been prepared for Tom, with guards posted. After a while, Moon had received a mirror call from the king and queen of the underworld.

"We wanted to thank you, Moon, for saving our boy, Tom" said Dave Lucitor.

"The Underworld Council still can't believe this; the Forbidden One loose once again" added Wrathmelior.

"If it is at all possible, could Star be returned to us unharmed?" hoped Moon.

"Our guard knows how to dislodge the Forbidden One from his host, but due to the nature of his chosen body, it won't be easy if he resists" pressed Dave. Then, an advisor whispered something in Dave's ear. He asked for clarification, to which the advisor confirmed, and then he disappeared from view.

"Things just got worse, Moon. According to latest intelligence, the Forbidden One is massing an army to take Butterfly Castle, and Tom. We'll be sending our best forces to assist you, but against him, the odds are slim" clarified Dave. Moon thanked the Lucitors for their aid, and terminated the call. She made her way to the head of the royal guard.

"Inform the knights that there is an impending attack on this castle, and ready the defences. As of this moment, Mewni is on the eve of war" Moon ordered. The head knight acknowledged the order, and set about their task.

Author's note: I never wrote this to be a 20-chapter story like the Excalibur Saga, so the next chapter may be the final one. I find that the longer the story goes on, the more it starts to drag. I'm still finding the optimum length and number of chapters a story needs to be. That, and I honestly keep forgetting about this fic, considering I've been playing Pokemon Ultra Sun most of the time. The usual disclaimers, I own nothing. Daron Nefcy owns SVTFOE, Alex Hirsch owns Gravity Falls, and Disney owns both. Enjoy.


	5. Star-studded rescue

**Star-studded rescue**

The knights of Mewni were rushing around, preparing the castle for a siege by Bill's forces. Many of the civilians in the immediate vicinity were evacuated, but those that say they can swing a sword and are willing to fight, or were part of the reserves, were given armour and told to report to the castle for assignment. Moon was co-ordinating with the underworld forces sent by Dave and Wrathmelior, while the High Commission saw to Tom's defence.

"Bill needs Tom to break out of the Land of the Vanquished, which means we can safely assume that every Nightmare soldier has been given orders to take him alive. We will be placing honour guards from both Mewni and the Underworld outside Tom's designated safe room, while the majority of our forces will be stationed on the walls and ramparts to repel the coming attack. Any questions?" Moon briefed the knights.

"What do we do when, or if, the castle walls are breached, ma'am?" asked one of the knights.

"In the event of a breach, all units will fall back to the courtyards to bolster our interior defence, but with any luck, that will not be necessary" answered Moon.

"What about Star? Her body is still under Bill's control" pointed out Marco.

"The Underworld forces know how to dislodge Bill from her body, but it is our hope that he will not take part in the opening assault. But, I assure you, dear, the knights have been told not to land any lethal blows to her" assured Moon.

"Your Majesty! We have incoming!" called a tower guard. Sure enough, an army of monsters came to the castle gates, but their leader was waving a flag of truce.

"Let them in" Moon ordered, and the drawbridge was lowered. The battalion leader came forth to address Moon.

"Buff Frog?!" Marco exclaimed in surprise.

"Good to see you again, Karate Boy" Buff Frog replied, using Marco's affectionate nickname.

"I assume you know what's going to happen?" inquired Moon.

"Yes, I do. I put out a call to arms. Many monsters were unwilling, but I told them what Star had been doing for monster-kind. It took some kind words from my daughter Katrina for them to come around. Unfortunately, for every monster you see here, two more are supporting Toffee, there was much in-fighting" Buff Frog confirmed. Moon had not expected monster support, but she was grateful for it nonetheless. She put some monsters on the exterior defence, and others to the interior. Then she turned to Marco.

"You should go back to Earth. I can't guarantee your safety if you remain here, and I don't want to see you hurt, or worse" Moon pressed.

"I can't leave Star, not to Bill. She came to rescue me from his clutches, it's time for me to return the favour" Marco insisted.

"This isn't a discussion. I'm sorry, Marco, but you're going back whether you want to or not" Moon concluded, and she took his scissors, cut a portal to the Diaz house, and shoved Marco through. Marco made to go back through, but the portal was already closed.

"You did what you had to" assured Buff Frog.

Marco landed on the front porch of his house on Earth, and his parents rushed outside to greet him.

"Marco, my boy! Come inside, we can catch up, it's been too long" greeted Rafael. When Marco turned to face his parents, they noticed his grim expression. Angie rushed forward to embrace Marco, her motherly intuition kicking in. When the Diaz family got inside, Marco explained everything.

"Marco, honey. I know you hate doing nothing, but Moon is right, it wasn't safe there. I may not know her that well, but now she has my utmost respect, because she did what was right, and sent you back to us" said Angie.

"What am I supposed to do now? Go back to how things were before? Wake up, get the school bus, come back home, do homework and go back to bed" Marco pondered.

"Like us normal folk" chimed Rafael.

"You don't get it, do you? If Bill gets what he wants on Mewni, then all is lost. The Cipher War will begin again and this time we won't be able to stop him. It's not about seeking adventure and excitement, it's about saving what we all hold dear" Marco clarified.

"I'm sure Moon has everything under control. Sometimes it's better to leave things to the professionals" Angie counselled. Marco was not convinced, but he did not feel like arguing any further. Instead, he went to his bedroom, to try and get some sleep. He thought about Angie's words about leaving it to the professionals, and then it hit him. Who had more experience fighting Bill than anyone he knew? Then he remembered the Pines twins, the heroes who defeated Bill the first time around. Marco could ask them for help. He switched on his laptop, logged onto his social media account, and messaged Dipper. After the Cipher War, Marco was familiar with all who fought that day, Milo Murphy, Phineas and Ferb, and the Pines twins, to name a few.

"Dipper, I need your help" Marco messaged.

"What is it?" Dipper replied, then Marco told him the story of the Book of Avalon, how it was a piece of Bill left over, and how a pitched battle was about to get underway to prevent Bill from getting out of the Land of the Vanquished.

"I see, well I still have contacts at Excalibur I can talk to. They can lead people into Mewni to assist with the defence, but I'd like you to stay where you are" Dipper instructed.

"What?!" Marco responded.

"Dude, I know where you're coming from, I hate standing on the sidelines too, but that castle is going to be a warzone, and if Excalibur goes in, they probably won't be able to keep you safe. Trust me, Excalibur are trained for this, they can handle it" Dipper reasoned. Marco did not know how to respond to that, or even if he should.

"I know you want to rescue Star and be a hero, but what good is a hero, if he's dead?" Dipper added. Marco knew he was not going to win this one.

"Fine, but promise me Excalibur will do everything they can to ensure Star survives. It may be Bill in control, but Star is looking to take her body back" Marco urged.

"I've been there, I know what it's like to watch your body be used for evil by him. I can promise you Star will come to no harm" Dipper assured. Marco then logged off, and resumed his efforts to find sleep.

At the Excalibur Institute, Albert was overseeing what he liked to call the Public Relations division, when the team's real objective was to keep the general population from finding out about Excalibur. They had, so far, been able to deflect any suspicions the public had about a 'super secret' government organisation conducting the dark research that led to Bill's ascension, by blaming it on a super rare cosmic event that only took place once every 10 million years. Even he had to admit that this ruse was never going to hold up under close scrutiny, but he hoped that since there weren't any records of what actually happened 10 million years ago, no-one would pay the theory any mind.

"How long do you think people are going to believe this, sir?" asked the division head, Evelyn.

"To be honest, I don't expect them to believe it at all. But it's the best we've got. It may buy us some time, at least" Albert answered. Just then, Kilstone, Albert's XO, walked in.

"Sir, you have a priority call from Major Smith in your office" Kilstone briefed, and Albert left to take the call. Once Albert got to his office, he found the anonymised image of Major Smith on his monitor.

"Yes, Major?" Albert acknowledged.

"We've had a recent development in Mewni. It seems Marco Diaz has arrived on Earth bearing news that Butterfly Castle is or will be under siege by the Nightmare Legion very soon" Major Smith summarised.

"I did get a call from Queen Moon quite recently. She said that her daughter, Star, found an old book cursed with Bill's magic, and has been corrupted by its influence. It would appear that Moon was successful in extracting a demon called Tom from a ritual that would've seen Bill resurrected" Albert explained.

"So it would seem. I would like to know why you didn't inform me of this development" Major Smith inquired.

"At the time, it was an internal Mewni affair. I didn't feel that it was a homeworld security issue, and that Moon and her team could destroy the artefact without us getting involved" Albert justified, rather weakly.

"With Bill Cipher, nothing should be left to chance. If he is successful in getting Tom back, the devastation he could inflict is too ghastly to think about" scolded Major Smith.

"Are you authorising the use of Excalibur's forces to assist the Mewmans?" quizzed Albert.

"To prevent a second Cipher War, yes. Have you the means to get to Mewni?" responded Major Smith.

"We have, sir, but only foot soldiers. We cannot get the portal stable enough to transport vehicles and heavy artillery" Albert informed.

"It'll have to do. Make preparations and deploy as many men as you feel necessary. One more thing, the Mewman princess may be under Bill's control. You can use lethal force against the Nightmare Legion, but I want her unharmed. Try and free her, if you can" instructed Major Smith.

"Yes, sir. I'll make sure every man knows the drill" Albert confirmed, and the call was terminated. Albert then summoned Kilstone, and gave him and as many men as the institute can spare their marching orders.

"I've been waiting to get some payback for last time" Kilstone remarked.

"Careful, Jake. Revenge is not our only aim. We go in to prevent his return. If any man finds the book, destroy it. Otherwise, the goal is to assist the Mewmans, nothing more or less" Albert cautioned. Just then, Albert's yeoman spoke over the comms.

"Excuse me, sir, but there's a boy called Marco Diaz outside, asking to see you. Should I let him in?" inquired the yeoman.

"See him to my office, please" Albert replied. The yeoman acknowledged the order, and the call was cut.

"Kilstone, you're in charge of the forces going to Mewni while I see to Marco. That castle must hold at all costs, understood?" Albert said, urgently. Kilstone confirmed the order, and each left to their assignments. When Albert returned to his office, as expected, he found Marco, who was panting like he ran an entire marathon.

"I never thought I would see you here again, given the circumstances of your last visit. I take it you're here because you want to help Star?" Albert surmised.

"I can't just sit by and watch while others do all the fighting. Star's my one and only. I have to go and help" Marco insisted.

"Ordinarily, I'd be telling you to leave things to the grown-ups, but I remember that it was children who saved us from Bill last time, and children who helped the time before that. So, I have decided to let you join the fight. But on one stipulation, I'm coming with you" Albert bargained. Marco agreed to this, and Albert opened a small cupboard in his office.

"There's more than one reason this institute is called Excalibur" Albert added, and he produced two swords from the cupboard. "Do you know how to swing one of these?"

"I've had much practice" Marco answered, and he took one of the swords.

"My guess is that Bill-Star will be withdrawn from the opening conflict, so our job will be to go behind enemy lines, and free her before the serious fighting begins. These sedatives will knock her body out, allowing our Star to take back control. If we can recover the book, all the better, but she is our first priority" Albert briefed. Marco confirmed the orders, and he and Albert made for the portal in the vault to Mewni, but programmed different entry co-ordinates from the forces deployed to the castle defences, and went through.

Back at Butterfly Castle, Moon and the High Commission were alerted to a portal opening in the courtyard, but instead of the Nightmare Legion, men from the Earth Dimension arrived with their weapons. Their leader addressed Moon.

"Your Majesty, Lieutenant Jake Kilstone, reporting as ordered by Captain Albert Stevens of the Excalibur Institute. He sent us to assist you in the defence of this castle" Kilstone stated.

"We could use those long range weapons on the ramparts, and see if you can help fortify the castle gates" Moon directed, and the men got to work. Moon then found Eclipsa, and together, they conjured a magical shield that enveloped the castle. Eclipsa added her own little spin by conjuring thorny vines to cover the outer gate. Moon noted that throughtout everything, Eclipsa, barring the escape from her dungeon cell, made no hostile manoeuvres. Maybe, Moon thought, Eclipsa isn't as bad as she was led to believe. True, she dabbled in dark magic, but then again, Moon herself had used at least one dark spell in defence of her kingdom.

"You know, Star reminds me a lot of myself, when I was her age" mused Eclipsa. Moon chuckled, weakly.

"She is unique. Dedicated to her convictions, never wavering from what she thought was right, and always so full of energy" Moon added.

"We should get her back ourselves. We're her family, the responsibility falls to us" Eclipsa suggested.

"I can't believe I'm saying this, but I agree" Moon said, and the two women made preparations for a rescue.

"Where do you think you're going?" interrogated Hekapoo.

"To rescue my daughter. I'm leaving you in charge of the defence. Hold out until we return" Moon answered, firmly, and she and Eclipsa portalled out to wherever Star may be.

"You do realise what may happen if Eclipsa gets her hands on that book?" Rhombulus asked cautiously.

"I do, but I don't want to get in the way of a mother rescuing her daughter. Plus, Moon can keep Eclipsa in check" Hekapoo assured, and the High Commission took charge of finalizing the defence plans. The Mewman knights and monsters were placed on the castle walls, Excalibur snipers were positioned on the highest towers, and the Excalibur infantry were garrisoned in various buildings in the courtyard, ready to assist in interior defence whenever the gates were breached. Kilstone, Buff Frog and the High Commission were in the command room, co-ordinating deployments. Soon enough, the Nightmare Legion arrived at the front gates. The few nightmare soldiers that dared to approach found themselves fried by the magical shield that Moon and Eclipsa had cast before their departure.

"Yeah, who's scary now?!" Rhombulus retorted. The nightmare soldiers had no choice but to hold off their attack.

Albert and Marco found themselves on a cliff, far from the edge. They couldn't see anything resembling a command post or main camp, but they did find some ruins. Albert and Marco went to investigate, and found Toffee and Bill-Star.

"That shield is going to be a problem if it remains intact. Deploy the heavy artillery and bombard the castle for as long as you can" Toffee ordered a nightmare soldier, and the said soldier left to carry out the order. Bill-Star was visibly struggling.

"You won't take back control that easy, princess!" rebuffed Bill-Star.

"So, you do have a weakness after all, Bill" called Albert, making his entrance alongside Marco.

"WHAT?! How did you two find me?" Bill-Star demanded.

"Probably the same way we did" answered a voice from across the way. It was Moon, accompanied by a woman Albert had never seen before.

"Don't tell me, Eclipsa Butterfly. I have a bone to pick with you" Toffee seethed.

"This is Toffee? I told you to aim for the heart" Eclipsa remarked.

"A mistake I'm keen to rectify" Moon responded. The sounds of the shield being shelled filled the air, as the stand-off continued. Bill-Star laughed.

"Within minutes, that castle will be nothing but rubble, and my return will be assured" Bill-Star monologued.

"I wouldn't count my chickens just yet, Bill. Us mortals can still surprise you" Albert replied, and the artillery was soon destroyed by Excalibur rocket fire. Bill-Star got so frustrated, he fired a devastating beam from the wand, which collapsed the shield. Using this distraction, Albert fired a sedative dart from his watch at Bill-Star's neck. Reeling from the effects, Bill-Star tried to stay awake, but couldn't and he collapsed. On the astral plain, Bill fell out of Star's body, allowing the real Star to take control.

"A pity, but his arrogance and cocky nature would eventually get the better of him. Unfortunately, for you, I have no plans to stop this assault, nor will I allow you to take the book" Toffee said.

"You're not exactly in a position to make threats. It's four of us against one of you" Albert warned.

"And two of us know how to put you down permanently" Eclipsa added.

"Maybe so, but I still have this" Toffee retorted, and opened the book, allowing its darkness to engulf him.

"I'm fairly sure the book doesn't do that" Marco pointed out.

"The darker the reader, the quicker the book takes control" explained Albert, and sure enough, Bill-Toffee was born.

"Invincible lizard man, I'd say this is a step up" Bill-Toffee remarked, and he slid the book into his inside blazer pocket. Star was starting to come around, and saw Toffee standing behind her. She blasted him with one of her spells, which put a hole in his chest, allowing her, Marco and the others to escape. Bill-Toffee, of course, regenerated, but not before they got away through a portal. They ended up inside the command room, where the High Commission, Kilstone and Buff Frog were waiting.

"It's alright, she's free" Moon assured everyone, and their weapons were lowered. Star was still struggling to stand, so Buff Frog got her a chair.

"What was in that dart?" Star asked, hazily.

"Standard issue sedative, for short term pacification of the target. Useful for getting people de-possessed. Try not to move, side effects include dizziness, nausea and temporary loss of sight" Albert outlined.

"That'll explain why Marco is a big, red blur" Star said.

"Don't worry, it'll only last a few minutes" Albert assured. He then asked Kilstone for a battle report.

"With the shield down, it's only a matter of time until the Nightmare Legion storms the castle. Fortunately, we've finished troop deployments and have brought in additional heavy weaponry to counter any siege weapons they may have" Kilstone reported.

"We have another problem. Bill may be out of Star but his next host is a lizard, someone called Toffee. Star shot him at point blank range in the chest and he got up like it was nothing. Worse still, we were unable to destroy the book" Albert briefed.

"We defeated Toffee once, we can do it again" Marco piped up.

"Yes, but the one who did it without dark powers is not in the best shape, and there's no guarantee Toffee will join the fighting" Moon corrected.

"Then we'll go back again, try and destroy the book with a simple fire spell, engulf them both in flames" Eclipsa suggested.

"Bill-Toffee will be ready for that, he'll most likely be somewhere we can't reach him" Albert countered. A messenger had come into the command room with urgent news.

"News from the front. The enemy army is storming the gates. One of the men spotted a lizard with them" reported the messenger, and they all went out to look. Through Kilstone's binoculars, Albert saw Toffee, on the front lines.

"Well, we can't get to him there. Looks like our only option is to hold out as long as possible, and destroy Bill-Toffee when he gets inside. Hopefully, Star will be fit enough to fry him by then" Albert concluded. Hekapoo gave orders for a volley of arrows to rain on the enemy, and the Excalibur snipers started picking targets. The battle had begun in earnest.

Author's note: I know I said last time that this may be the final chapter. I would like to emphasise the 'may' part of that statement. I didn't want to make this chapter overly long (it's almost 3500 words as is) so I've decided to take the Hollywood approach and split the final part of this fic into two. That, and I really hate odd numbers, so an even 6 chapter story is more appealing. I apologise if the final chapter turns out to be a bit of a slog, but I don't see how I can prolong a castle siege, I've never wrote one before. Maybe I'll ask Peter Jackson how he did it. The usual disclaimers, I own nothing, Daron Nefcy owns SVTFOE, Alex Hirsch owns Gravity Falls, and Disney owns both, Enjoy.


	6. Battle of Butterfly Castle

**Battle of Butterfly Castle**

As the fighting continued outside the castle gates, with archers and snipers taking shots at the horde laying siege to Butterfly Castle, Bill-Toffee ordered rams to break down the gate. The equipment arrived, and approached the entrance, looking to break the door in. However, Eclipsa's spell held true. As soon as the ram approached, it was engulfed in vines, and swallowed into the earth. Frustrated, Bill-Toffee ordered catapults to try and punch a hole in the castle walls, but Excalibur was ready for that. A few well-aimed rockets destroyed the equipment. This did not deter the Nightmare Legion, as the catapults in reserve then took aim at the sniper's perches, where the anti-armor units were based. Back and forth this exchange of fire went on, neither side giving an inch. In the command room, Star was still struggling to see straight.

"What is all that racket? My head's pounding enough as it is" Star asked dozingly.

"The castle's under attack, Star. We're holding for now, but I'm not sure for how long" Moon answered.

"The way I see it, the fighting only ends in one of two ways. One; the book is destroyed and Toffee along with it, or two, the forbidden one makes his big comeback. I know what you said about Toffee, but no-one is truly invincible. He must have a weakness" Albert briefed.

"Long ago, I had a chance to kill Toffee, and failed. I will not make that mistake again. I know the spell, and this time, I'll aim for the heart" Moon assured.

"You're really contemplating using Eclipsa's spell again? After what her magic did to you? There's no telling what will happen" Hekapoo interjected.

"To save my kingdom, I'll do anything, even use dark magic" Moon replied.

"There is no need for you to further corrupt yourself, Moon. I can do it" offered Eclipsa.

"Regardless, we need to plan quickly. I doubt Toffee is taking his sweet time out there" Albert pressed. As he said this, Kilstone's voice came over the radio.

"Sir, anti-armor units are exhausted, and snipers say the enemy is scaling the walls with ladders" Kilstone reported.

"Pull all sniper units back, and position them on strategic rooftop points in the courtyard to supplement the garrison" Albert ordered. Kilstone acknowledged the command, and proceeded to carry out the instructions.

"It's only a matter of time until that army opens the door to the castle. I'd better reinforce the door to Tom's safe room" Rhombulus said.

"I'll see Star and Marco to the throne room and have it sealed off. That should keep them safe" Moon added, and took the teens to said room.

"I know some people I can ask for reinforcements. More than one of them owes me a favour" Hekapoo volunteered, and she left in her portal to parts unknown. This left Omnitraxus, Albert, Eclipsa, Wrathmelior and Buff Frog to co-ordinate the remaining units inside the castle.

"So far, the walls are holding. Our knights are keeping the enemy at bay, but more will come" Omnitraxus outlined.

"With close quarters combat on the walls, my snipers will not have a clean shot" Albert added.

"I can order additional monster units to reinforce the walls if needed" suggested Buff Frog.

"That will allow my men to hold the courtyard if they get through" Albert said, and Buff Frog gave the order for his monsters to see to the wall defence.

"I will have my demonic forces plug up any side entrances the enemy may use. It will force them to engage us where we're more prepared for them" Wrathmelior offered, and she and Omnitraxus saw to sealing all entryways, except one, and that one entryway was being seen to by the Honour Guard protecting Tom.

"If I may, now that the defences are secured, what about Toffee himself?" asked Eclipsa.

"Our first priority is ensuring the castle holds long enough to draw Toffee out. Then we can order a precision strike to end this whole thing right now" Albert explained.

"Yes, but if he decides to use the book's powers against us, we'll be in real trouble" Eclipsa countered.

"I hate to admit it, but she does have a point. This castle will not last five minutes if the book's powers are used in full" Omnitraxus conceded. As if on cue, a massive explosion came from outside. When everyone went to look, they found a massive hole in the castle walls, and from it, legions of Nightmare soldiers burst forth.

"Well, it seems we have even less time than five minutes, Omnitraxus" Albert commented, and he gave orders for all wall forces to pull back to the courtyard to try and seal the breach. As gunfire from Excalibur soldiers could be heard, Albert came up with an idea. If they could get Tom out of the castle without being noticed, the Nightmare Legion would not enable Bill's return, even if the castle was taken. It was a desperate strategy, but as the battle drew on, the chances of victory were growing slimmer. He made for Tom's room, and conveyed his plan to Rhombulus.

"It's a long shot, but it might work. Evacuate Star and Marco while you're at it. Do you have another safe house in mind?" Rhombulus inquired.

"My home base on Earth can withstand an invasion like this. I can hide Tom and the others there, and we can regroup any remaining forces there should the battle turn" Albert suggested. Rhombulus agreed, and opened the door to the room.

"I heard everything, and I am not going to let other people do the fighting for me!" Tom insisted.

"It's chaos out there, Tom. If Bill catches you, it's game over for everyone. Like it or not, your safety is the key objective in this battle. The castle may fall, but without you, the forbidden one has still lost" Albert explained.

"Fine, but not without my friends" Tom said, and he and Albert made for the throne room to evacuate Star and Marco. Moon undid the defensive spells she cast on the door, and let Star and Marco out. Marco made to open a scissor portal to Excalibur HQ, but found that he couldn't. He tried many times, but a stable portal would not form. Then, a voice came ringing through the castle that made everyone shiver in fear.

"If you were hoping to get the kiddly-winks out of the castle, you're out of luck. A simple portal jamming spell has seen to that. Now hand over the demon boy and spare your armies any further bloodshed!" Bill-Toffee demanded. Moon was beside herself with despair.

"Now what do we do? We can't run, no way am I handing over Tom, and the fight, dare I say it, will be lost" Moon worried.

"Our only option is to make a beeline straight to Toffee, but there's hundreds of nightmare soldiers between us and him" Albert summarised. Star, who had ducked away to another room in the castle without anyone noticing, a skill she was disturbingly good at, emerged with what looked like unicorns, only angrier.

"Then, we ride out and face them head on. A couple of these can get us to Toffee easy" Star suggested.

"A full-on charge, the enemy will not expect it, and those mounts look mean" Albert surmised. Marco and Star had already climbed onto their horses, Tom had just gotten onto one, and Albert was making to mount his own. Moon would object to the idea, had there been any other options on the table. She got a warnicorn of her own, and joined the charge.

"Hey, Marco, bet I get more than you, may the best prince win" Tom wagered, and the group charged into the courtyard, which looked the part of a fierce battle.

"Kilstone, clear us a path" Albert said into his wrist communicator, and the Excalibur soldiers, as well as everyone else, saw either their boss, their queen, their prince/princess or a kid in a red hoodie charging the enemy, mowing down any nightmare soldiers that were in their way, Star blasting away with her wand, and Tom throwing fireballs at them. This boosted morale, and the battle became winnable. It would be difficult, but not impossible to hold the castle now. As if to add to the good news, Hekapoo emerged, with a battalion of what looked like biker gangs, but it was not motorcycles they were riding, but what looked like cycle/dragon hybrids.

"Dragoncycles, now we can win" Marco commented, and a dragoncycle approached him, and invited him to ride. "Nachos, good to see you boy" Marco added, and he got on.

"You named your dragoncycle Nachos?" Tom commented. The dragoncyclists were tearing into the enemy, and cleared the way to Toffee. Albert and the others encircled him, as if to end things here and now.

"What do we have here, an exiled prince, a rash princess, my old plaything, my ticket to freedom and an aging monarch, all in one place, and it's not even my birthday" Bill-Toffee listed.

"They're not alone" came a voice behind them. Eclipsa came to join in, as well as Hekapoo, Rhombulus, Wrathmelior and Omnitraxus.

"It's ten against one, Bill. You're not winning this one, even in the body of an immortal" Albert warned.

"Stand down, hand over the book, and submit to crystallisation!" Rhombulus demanded.

"Like I want to be part of your rock collection!" Bill-Toffee retorted, and threw everyone back with a 360-degree shockwave. Just as Bill-Toffee was about to grab Tom, he was pushed back by an energy blast. Then, a purple-haired warrior lady came descending into the arena.

"Mina Loveberry?" Star remarked.

"Am I late to the party?" Mina asked.

"No, in fact you came in time for the main event" Albert answered.

"I don't care how many of you there are. I'll be free of the Land of the Vanquished soon enough. Nothing can stop me! I am the King of Nightmares!" Bill-Toffee declared, and battle began. Although Eclipsa tried her hardest to restrain Bill-Toffee with her vines, he kept cutting free. Star then tried sticking him to the floor with syrup spells, but all that did was stain his suit, which angered Bill-Toffee immensely. Rhombulus tried crystallising him, but he kept breaking free. Marco and Albert kept slicing hands off, but they grew back just as fast as they were dismembered. Tom and Hekapoo tried pyrokinesis, but that only succeeded in burning the battle site, limiting the movement of their own team. Omnitraxus tried grabbing him, but he always broke free, and Bill-Toffee kept dodging Moon's and Mina's energy blasts.

"Is this battle over? I'm bored!" Bill-Toffee groaned, looking at the exhausted battle group arrayed against him.

"You kidding? I can do this all day" Marco panted, convincing no-one. Just then, Bill-Toffee froze in place.

"What's happening?" Bill-Toffee strained to ask. It was apparent that, in the struggle, Bill's hold on Toffee was weakening. He had spent most of his energy fending off the attacks that the real Toffee had a fighting chance of freeing himself from the book in the same manner that Star did.

"Knock him out, quickly!" Moon pressed. Albert then shot another sedative dart at Bill-Toffee, and this, surprisingly, did the trick. Albert was not sure a dart meant for humans or similar would work on lizard people. Once Toffee was knocked out, and Bill dislodged, Moon quickly searched the pockets of his suit, and found the book, undamaged in the fighting. Tom used some more fire to burn the Book of Avalon, destroying it once and for all. The evil of Bill Cipher was finally eradicated, and Marco felt free. He had faced his demons, literally, and finally came to terms with his traumatic experience, and prepared to move on, with Star.

The Nightmare soldiers laying siege to Butterfly Castle had disappeared back to their realm, and a cry of victory could be heard from all around the castle. The citizens that had evacuated returned to their homes, and work began to rebuild what was destroyed. There was just one more problem to deal with. Toffee was coming around. Eclipsa restrained him with vines, and turned to Moon.

"Do you want to do it, or should I?" Eclipsa asked. Moon thought, and came to a decision.

"No, there's been enough killing and dark magic in this kingdom" Moon concluded. Toffee laughed at this display of mercy.

"I'm surprised at you. All this work to finish me, and you won't do it. You know I'll just come back with a monster army and pick up where we left off" Toffee taunted.

"No, you won't" Moon responded, and she signalled to Rhombulus, who crystallised Toffee.

"I suppose you'll want to crystallise me too, then. I did start all this, after all" Eclipsa mused.

"Yes, you did. But you also helped us finish it. For that, I believe you've earned your freedom" Moon granted. The High Commission agreed to this conclusion, albeit reluctantly, and the group left for their respective homes. Albert to Earth and Excalibur, Tom to the underworld, and the rest to Butterfly Castle, to aid in the rebuilding effort.

"It feels like we just finished cleaning up after Toffee, now we got to start all over again" Marco joked.

"Well, look around. Mewmans and monsters are working together. For all that's happened, you got to take the positives where you can" Star said. Marco chuckled.

"Like spending more time with you" Marco flirted, and embraced Star.

"Something like that" Star countered, equally as flirtatious, and kissed to a job well done. Then, Tom came back from the Underworld briefly.

"My count was 34, how many did you get?" Tom asked. Marco was nervous at this. In all the chaos, he forgot about his little game with Tom.

"Errrr...35. I honestly lost count in all the excitement" Marco answered.

"You know what that means, you forfeit" Tom teased.

"Hey, I wasn't really playing!" Marco countered playfully, and they all laughed.

Author's note: I finally got this done. Writing this only cements the fact that I am no good at anything to do with co-ordinated battles like you would see in LOTR or strategy games like Total War or Age of Empires. If I can help it, this will be the last fic I write with Bill in it. I feel like I've done all I can with our favourite flying nacho, and he needs a proper ending. The usual disclaimers, I own nothing. Daron Nefcy owns SVTFOE, Alex Hirsch owns Gravity Falls, and Disney owns both. Enjoy.


End file.
